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Article

The Role of Hydraulic Connectivity and Management on Soil Aggregate Size and Stability in the Clear Creek Watershed, Iowa

1
USDA-ARS (United States Department of Agriculture-Agricultural Research Service) National Laboratory for Agriculture and the Environment, Ames, IA 50011, USA
2
Hydraulics and Sedimentation Laboratory, Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996, USA
3
Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
4
College of Resource and Environment Sciences, Northwest A&F University, Yangling 712100, Shaanxi, China
*
Author to whom correspondence should be addressed.
Geosciences 2018, 8(12), 470; https://doi.org/10.3390/geosciences8120470
Received: 20 September 2018 / Revised: 19 November 2018 / Accepted: 7 December 2018 / Published: 11 December 2018
(This article belongs to the Special Issue Mechanics of Erosion: Process Response to Change)
The role of tillage practices on soil aggregate properties has been mainly addressed at the pedon scale (i.e., soilscape scale) by treating landscape elements as disconnected. However, there is observed heterogeneity in aggregate properties along flowpaths, suggesting that landscape scale hydraulic processes are also important. This study examines this supposition using field, laboratory and modeling analysis to assess aggregate size and stability along flowpaths under different management conditions: (1) tillage-induced abrasion effects on aggregate size were evaluated with the dry mean weight diameter (DMWD); (2) raindrop impact effects were evaluated with small macroaggregate stability (SMAGGSTAB) using rainfall simulators; and (3) these aggregate proxies were studied in the context of connectivity through the excess bed shear stress (δ), quantified using a physically-based landscape model. DMWD and SMAGGSTAB decreased along the flowpaths for all managements, and a negative correspondence between the proxies and δ was observed. δ captured roughness effects on connectivity along the flowpaths: highest connectivity was noted for parallel-ridge-till flowpaths, where δ ranged from 0–8.2 Pa, and lowest connectivity for contour-ridge-till flowpaths, where δ ranged from 0–1.1 Pa. High tillage intensity likely led to an increase in aggregate susceptibility to hydraulic forcing, reflected in the higher gradients of aggregate size and stability trendlines with respect to δ. Finally, a linear relationship between DMWD and SMAGGSTAB was established. View Full-Text
Keywords: aggregate stability; dry aggregate size distribution; hydraulic connectivity; agricultural management practices; rainfall simulator; erosion processes and mechanics; climatic and human impacts aggregate stability; dry aggregate size distribution; hydraulic connectivity; agricultural management practices; rainfall simulator; erosion processes and mechanics; climatic and human impacts
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MDPI and ACS Style

Wacha, K.M.; Papanicolaou, A.N.T.; Giannopoulos, C.P.; Abban, B.K.; Wilson, C.G.; Zhou, S.; Hatfield, J.L.; Filley, T.R.; Hou, T. The Role of Hydraulic Connectivity and Management on Soil Aggregate Size and Stability in the Clear Creek Watershed, Iowa. Geosciences 2018, 8, 470. https://doi.org/10.3390/geosciences8120470

AMA Style

Wacha KM, Papanicolaou ANT, Giannopoulos CP, Abban BK, Wilson CG, Zhou S, Hatfield JL, Filley TR, Hou T. The Role of Hydraulic Connectivity and Management on Soil Aggregate Size and Stability in the Clear Creek Watershed, Iowa. Geosciences. 2018; 8(12):470. https://doi.org/10.3390/geosciences8120470

Chicago/Turabian Style

Wacha, Kenneth M., A. N.T. Papanicolaou, Christos P. Giannopoulos, Benjamin K. Abban, Christopher G. Wilson, Shengnan Zhou, Jerry L. Hatfield, Timothy R. Filley, and Tingyu Hou. 2018. "The Role of Hydraulic Connectivity and Management on Soil Aggregate Size and Stability in the Clear Creek Watershed, Iowa" Geosciences 8, no. 12: 470. https://doi.org/10.3390/geosciences8120470

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